You will need to submit two updates. On one update, submit an add to the 2017 award page with the correct information. On the other update, submit a deletion request on the 2016 award page.
On both submissions, please include a short statement in the explanation box on why you are correcting the data. Include the URL of the official festival page with the awards information in the explanation box for proof.
I hope this helps. Please write back if you have any more questions.